Method of making device of a display
In a method of making device of a display, an insulating layer, a semiconductor layer, an ohmic contact layer, a second conductive layer, and a photoresist pattern are consecutively formed on a first conductive structure. The photoresist pattern includes a first thickness region, and a second thickness region outside the first thickness region. The thickness of the second thickness region is smaller than that of the first thickness region. In addition, in a gate driver on array (GOA) of a display, it includes a gate driver on array structure with a pull-down transistor. The pull-down transistor has a gate electrode, a semiconductor island, a source electrode and a drain electrode. The semiconductor island extends out of the edges of the gate electrode, the source electrode, and the drain electrode.
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1. Field of the Invention
The present invention relates to a gate driving circuit of a display, and a method of fabricating a device of a display, and more particularly, to a pull-down module of a gate driver on array (GOA) having high pull-down ability, and a method of making a device of a display capable of avoiding metal loss.
2. Description of the Prior Art
The conventional TFTs T3, T4 cannot provide pull-down effect when turned off. However, the start pulse voltage Vst or the clock signal Vck may have abnormal waveform during this period of time, and consequently the TFTs of the pixel regions may be turned on falsely. Thus, the pull-down ability of the conventional pull-down module requires to be improved.
Also, in the conventional photolithography process of display fabrication, for example 4PEP array processes, the size of the metal pattern actually formed is usually found smaller than its original designed size. This is so called metal loss, and the metal loss problem is serious particularly in patterning the second metal layer (Metal 2). This metal loss problem influences the reliability of the TFTs of pixel regions, the TFTs of gate driver on array (GOA), and other components e.g. photo spacer stages.
SUMMARY OF THE INVENTIONIt is therefore one of the objectives of the present invention to provide a gate driver on array of a display, and a method of forming a device of a display to solve the aforementioned problem.
According to the present invention, a method of forming a device of a display is provided. The method includes the following steps. First of all, a substrate is provided. Then, a first conductive layer on the substrate, and patterned to form a first conductive structure. An insulating layer, a semiconductor layer, an ohmic contact layer, a second conductive layer, and a photoresist pattern are consecutively formed on the first conductive structure. The photoresist pattern includes a first thickness region, and a second thickness region outside the first thickness region, and a thickness of the second thickness region is smaller than a thickness of the first thickness region.
According to the present invention, a gate driver on array of a display is also provided. The gate driver on array includes a substrate, and a gate driver on array structure. The substrate includes a peripheral region. The gate driver on array structure is disposed in the peripheral region. The gate driver on array structure includes a pull-down transistor, and the pull-down transistor includes a gate electrode, an insulating layer, a semiconductor island, a source electrode, and a drain electrode. The semiconductor island extends out of both edges of the gate electrode, and extends out of an edge of the source electrode and an edge of the drain electrode.
The semiconductor island of the pull-down transistor of the display extends out of the gate electrode, and also the source electrode and the drain electrode, and thus improves the pull-down ability. In addition, the method of the present invention uses a photoresist pattern with different thickness to perform photolithographic and etching processes for forming the pull-down transistor and photo spacer stage of the display, and therefore metal loss problem is diminished.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
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In conclusion, the semiconductor island extends out of the gate electrode, and also the source electrode and the drain electrode, and thus improves the pull-down ability of the pull-down transistor of the display. In addition, the method of the present invention uses a photoresist pattern with different thickness to perform photolithographic and etching processes for forming the pull-down transistor and photo spacer stage of the display, and therefore metal loss problem is diminished.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.
Claims
1. A method of forming a device of a display, comprising:
- providing a substrate;
- forming a first conductive layer on the substrate;
- patterning the first conductive layer to form a first conductive structure;
- consecutively forming an insulating layer, a semiconductor layer, an ohmic contact layer, a second conductive layer, and a photoresist pattern on the first conductive structure, wherein the photoresist pattern comprises a first thickness region overlapping the first conductive structure, and a second thickness region having a first portion and a second portion outside the first thickness region, a thickness of the first portion and the second portion of the second thickness region is smaller than a thickness of the first thickness region, and the first thickness region is located between the first portion and the second portion of the second thickness region.
2. The method of claim 1, wherein the thickness of the first thickness region is substantially between 1.5 and 2.5 microns, and the thickness of the first portion and the second portion of the second thickness region is substantially between 5000 and 6000 angstroms.
3. The method of claim 1, further comprising performing wet etching on a part of the second conductive layer not covered by the photoresist pattern.
4. The method of claim 3, further comprising ashing the photoresist pattern to thin the first thickness region and the second thickness region subsequent to performing wet etching on the part of the second conductive layer, wherein the thickness of the first portion and the second portion of the second thickness region is still smaller than the thickness of the first thickness region after ashing.
5. The method of claim 4, further comprising performing dry etching on a part of the semiconductor layer and a part of the ohmic contact layer not covered by the photoresist pattern and the second conductive layer subsequent to ashing the photoresist pattern.
6. The method of claim 5, further comprising removing the photoresist pattern subsequent to dry etching the part of the semiconductor layer and the part of the ohmic contact layer not covered by the photoresist pattern and the second conductive layer.
7. The method of claim 6, wherein the device of the display comprises a photo spacer stage, and the photo spacer stage is formed by stacking the first conductive structure, the insulating layer, the semiconductor layer, the ohmic contact layer and the second conductive layer.
8. The method of claim 3, wherein the photoresist pattern further comprises a third thickness region corresponding to a central part of the first conductive structure, wherein a thickness of the third thickness region is smaller than the thickness of the first thickness region.
9. The method of claim 8, wherein the thickness of the third thickness region is substantially between 5000 and 6000 angstroms.
10. The method of claim 8, further comprising ashing the photoresist pattern to thin the first thickness region and to remove the second thickness region and the third thickness region subsequent to performing wet etching on the part of the second conductive layer, wherein the second conductive layer is partially exposed after ashing the photoresist pattern.
11. The method of claim 10, further comprising performing dry etching on a part of the semiconductor layer and a part of the ohmic contact layer not covered by the second conductive layer subsequent to ashing the photoresist pattern.
12. The method of claim 11, further comprising performing dry etching on a part of the second conductive layer not covered by the first thickness region of the photoresist pattern to form a source electrode and a drain electrode subsequent to dry etching the part of the semiconductor layer and the part of the ohmic contact layer not covered by the second conductive layer.
13. The method of claim 12, further comprising etching a part of the ohmic contact layer not covered by the source electrode and the drain electrode and removing the photoresist pattern subsequent to dry etching the part of the second conductive layer not covered by the first thickness region of the photoresist pattern.
14. The method of claim 13, wherein the first conductive structure serves as a gate electrode, the device of the display comprises a pull-down transistor of a gate driver on array, and the pull-down transistor is composed of the gate electrode, the insulating layer, the semiconductor layer, the ohmic contact layer, the source electrode and the drain electrode.
15. The method of claim 8, further comprising ashing the photoresist pattern to thin the first thickness region and the second thickness region, and to remove the third thickness region subsequent to wet etching on the part of the second conductive layer, wherein the photoresist pattern partially exposes the second conductive layer, and the thickness of the second thickness region is still smaller than the thickness of the first thickness region after ashing the photoresist pattern.
16. The method of claim 15, further comprising performing dry etching on a part of the semiconductor layer and a part of the ohmic contact layer not covered by the second conductive layer after ashing the photoresist pattern.
17. The method of claim 16, further comprising performing dry etching on a part of the second conductive layer not covered by the first thickness region and the second thickness region of the photoresist pattern subsequent to dry etching the part of the semiconductor layer and the ohmic contact layer not covered by the second conductive layer.
18. The method of claim 17, further comprising etching a part of the ohmic contact layer not covered by the source electrode and the drain electrode, and removing the photoresist pattern subsequent to dry etching the part of the second conductive layer not covered by the first thickness region and the second thickness region of the photoresist pattern.
19. The method of claim 18, wherein the first conductive structure serves as a gate electrode, the device of the display comprises a pixel transistor, and the pixel transistor is composed of the gate electrode, the insulating layer, the semiconductor layer, the ohmic contact layer, the source electrode and the drain electrode.
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Type: Grant
Filed: Sep 9, 2008
Date of Patent: Nov 8, 2011
Patent Publication Number: 20090261339
Assignee: AU Optronics Corp. (Science-Based Industrial Park, Hsin-Chu)
Inventors: Tung-Chang Tsai (Hsin-Chu), Lee-Hsun Chang (Hsin-Chu), Ming-Chang Shih (Hsin-Chu), Jing-Ru Chen (Hsin-Chu), Kuei-Sheng Tseng (Hsin-Chu)
Primary Examiner: Angel Roman
Attorney: Winston Hsu
Application Number: 12/206,746
International Classification: H01L 21/00 (20060101); H01L 21/84 (20060101);